Introduction to Data Communication Systems

Data Communication

• Data communication refers to the exchange of data between two devices via a transmission medium, such as a wire or cable.

Components of Data Communication System

• A network is a set of devices connected by communication links, where each device (node) can send and receive data generated by other nodes.
• A link can be a cable, air, optical fiber, or any medium that can transport a signal carrying information.

Network

• A network is multiple computers connected together using a communication system to communicate and share files.
• The Internet is a communication system that has brought a wealth of information to our fingertips and organized it for our use.

Protocols

• A protocol is a set of rules that govern data communication, determining what, how, and when data is communicated.
• Key elements of a protocol include syntax, semantics, and timing.
• Syntax refers to the structure or format of the data and indicates how to read the bits.
• Semantics interprets the meaning of the bits and knows which fields define what action.
• Timing determines when data should be sent and at what speed it should be sent or received.

Role of Protocols

• Protocols determine how messages should be transmitted, the size of the window, and when to update each other.
• Protocols also govern how devices handle updates, new routes, and down links, and when to terminate a connection.

Network Criteria

• Network performance depends on network elements and is measured in terms of delay and throughput.
• Network reliability is measured in terms of availability and robustness, considering the failure rate of network components.
• Network security involves data protection against corruption and loss of data due to errors or malicious users.

Functions of a Network

• Resource sharing, such as network storage and backup devices, facilitates the way we live, learn, work, and play.

Types of Connections

• Point-to-point connections involve a single transmitter and receiver.
• Multipoint connections involve multiple recipients of a single transmission.
• Physical topology refers to the connection of devices and can be categorized as unicast, multicast, or broadcast.

Categories of Networks

• Local Area Networks (LANs) provide local interconnectivity over short distances.
• Wide Area Networks (WANs) provide connectivity over large areas.
• Metropolitan Area Networks (MANs) provide connectivity over areas such as a city or campus.
• Hybrid networks combine different network topologies.